Product:DSC 5401

This page contains information for the DSC 5401, a small interface board that provides two-way communications over RS-232 between a host computer and a DSC alarm system. The street price (in early '07) for this board is about $80.

I originally got a DSC 5400 interface board when my system was installed. This board is output only, and only posts major events (like "system armed", or "alarm"). It's really designed to write log messages to a serial printer. It does not provide you low-level access to individual zone status or status changes.

The DSC 5401 will provide the zone status details, and will let you manage the system from a host computer. For more information, see:

• Specification sheet
• Developer's Guide (includes detailed information about the RS-232 protocol)

Board Images

Here are images of the front and back of the board. The CPU is a 16F916, a flash programmable microcontroller from Microchip with 8K words of program memory. See: 16F916 datasheet. The 5 through-holes at the top of the board (directly above the microcontroller) appear to be programming pins for the 16F916.

The crystal is 14.31818 Mhz. The other chip on the board is a MAX232 clone (RS-232 level driver).

The jumpers are used to select the baud rate for the RS-232 interface: 4800, 9600, 19200, or 57600. There are two surface mount LEDs to show status: solid green indicates a good connection to the KEYBUS, and a red LED shows module status (blinking red is OK).

(Click on the images to access the high-resolution originals).

Installation

Installing the board on your DSC system will usually require access to the installer code, as you need to make the system aware that a new board is configured. If you have a monitored system, your monitoring service may be reluctant to give you that code, as it could be used to get access to monitoring information.

In my case, my alarm company had to come over and "bless" the new device, by entering magic codes with their installer code. I've used them for monitoring for years, and they did not charge for the visit (it took them all of 5 minutes).

I needed to fully power-cycle the system for the board to work properly.

Development

Writing apps for the interface board is mostly a matter of sending commands and receiving messages over the serial link. If you are just monitoring events, you don't even need to send any commands. The interface board will pass along messages. Here's some raw serial link data from my system:

6511CD
6100132B
6501CC
60901333
6511CD
6100132B
6501CC
60901333
6100132B
6501CC
60901333
6511CD

The first three characters are the message type (e.g. "609") and the last two are a checksum. The middle bytes (if any) are the data payload, which depends on the message type.